A magnetic resonance imaging apparatus requires a longer time for imaging than an X-ray CT apparatus and an ultrasonic apparatus, and hence tends to generate artifacts when imaging an object which moves due to body motion.
When, for example, the heart which moves due to respiration is an imaging target, it is known that the motion of the heart due to respiration is proportional to the motion of the diaphragm. There is therefore available a method of monitoring the motion of the diaphragm due to respiration by using navigator pulses upon setting the diaphragm as a reference position, and correcting the motion of the heart due to respiration by correcting the position where an MR signal is acquired, based on the position of the diaphragm, using transform such as translation. There is available another method which stores an acquired MR signal and the position information of the diaphragm at the time of the acquisition as a combination in advance, and reconstructs image data after correcting the acquired MR signal based on the position information of the diaphragm. These methods can capture an MR image (second image data) with little motion artifact.
The relationship between the motion of the diaphragm and the motion of the heart differs for each object. Calculating a transform parameter for correction (body motion correction parameter) for each object will improve the accuracy of motion correction.
A conventional magnetic resonance imaging apparatus captures an MR image (first image data) for monitoring a reference position and the body motion of an imaging target. The apparatus automatically calculates a body motion correction parameter for each object from the first image data. The apparatus captures the second image data by using the calculated body motion correction parameter (e.g. JP-A 2002-28150 (KOKAI)).
An imaging target such as the heart has more complex motion due to body motion, and may change its shape and position even if a reference position remains the same. For this reason, even when a body motion correction parameter is calculated for each object and the body motion of the imaging target is corrected by translation or transform with higher order than translation, correction errors occur. The errors differ in amount at each position on the imaging target.
The conventional magnetic resonance imaging apparatus cannot check to which degree body motion can be corrected at each position on an imaging target by a set body motion correction parameter.